diff --git a/Classes/AllowModules/AllowModuleInterface.php b/Classes/AllowModules/AllowModuleInterface.php
new file mode 100644
index 0000000..959d323
--- /dev/null
+++ b/Classes/AllowModules/AllowModuleInterface.php
@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DigiComp\FlowMaintenanceMode\AllowModules;
+
+use Psr\Http\Message\ServerRequestInterface;
+
+interface AllowModuleInterface
+{
+    public function isRequestAllowed(ServerRequestInterface $request): bool;
+}
diff --git a/Classes/AllowModules/ByCookieAllowModule.php b/Classes/AllowModules/ByCookieAllowModule.php
new file mode 100644
index 0000000..a6f7b24
--- /dev/null
+++ b/Classes/AllowModules/ByCookieAllowModule.php
@@ -0,0 +1,35 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DigiComp\FlowMaintenanceMode\AllowModules;
+
+use Psr\Http\Message\ServerRequestInterface;
+
+class ByCookieAllowModule implements AllowModuleInterface
+{
+    protected ?string $cookieName;
+    protected ?string $cookieValue;
+
+    /**
+     * @param string|null $cookieName
+     * @param string|null $cookieValue
+     */
+    public function __construct(?string $cookieName, ?string $cookieValue)
+    {
+        $this->cookieName = $cookieName;
+        $this->cookieValue = $cookieValue;
+    }
+
+    public function isRequestAllowed(ServerRequestInterface $request): bool
+    {
+        $cookies = $request->getCookieParams();
+        if ($this->cookieName === null || !isset($cookies[$this->cookieName])) {
+            return false;
+        }
+        if ($this->cookieValue !== null && $cookies[$this->cookieName] !== $this->cookieValue) {
+            return false;
+        }
+        return true;
+    }
+}
diff --git a/Classes/Exception.php b/Classes/Exception.php
new file mode 100644
index 0000000..cd10935
--- /dev/null
+++ b/Classes/Exception.php
@@ -0,0 +1,9 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DigiComp\FlowMaintenanceMode;
+
+class Exception extends \Neos\Flow\Exception
+{
+}
diff --git a/Classes/Http/MaintenanceModeMiddleware.php b/Classes/Http/MaintenanceModeMiddleware.php
new file mode 100644
index 0000000..5527d77
--- /dev/null
+++ b/Classes/Http/MaintenanceModeMiddleware.php
@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DigiComp\FlowMaintenanceMode\Http;
+
+use DigiComp\FlowMaintenanceMode\AllowModules\AllowModuleInterface;
+use DigiComp\FlowMaintenanceMode\MaintenanceModeActiveException;
+use DigiComp\FlowMaintenanceMode\MaintenanceModeManagerInterface;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\ServerRequestInterface;
+use Psr\Http\Server\MiddlewareInterface;
+use Psr\Http\Server\RequestHandlerInterface;
+
+class MaintenanceModeMiddleware implements MiddlewareInterface
+{
+    protected MaintenanceModeManagerInterface $maintenanceModeManager;
+
+    /**
+     * @var array<array-key, AllowModuleInterface>
+     */
+    protected array $allowModules;
+
+    public function __construct(
+        MaintenanceModeManagerInterface $maintenanceModeManager,
+        AllowModuleInterface ...$allowModules
+    ) {
+        $this->maintenanceModeManager = $maintenanceModeManager;
+        $this->allowModules = $allowModules;
+    }
+
+    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
+    {
+        if ($this->maintenanceModeManager->isMaintenanceMode()) {
+            foreach ($this->allowModules as $allowModule) {
+                if ($allowModule->isRequestAllowed($request)) {
+                    return $handler->handle($request);
+                }
+            }
+            throw new MaintenanceModeActiveException('Maintenance is active');
+        }
+        return $handler->handle($request);
+    }
+}
diff --git a/Classes/Http/MaintenanceModeMiddlewareFactory.php b/Classes/Http/MaintenanceModeMiddlewareFactory.php
new file mode 100644
index 0000000..cc52efb
--- /dev/null
+++ b/Classes/Http/MaintenanceModeMiddlewareFactory.php
@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DigiComp\FlowMaintenanceMode\Http;
+
+use DigiComp\FlowMaintenanceMode\MaintenanceModeManagerInterface;
+use Neos\Flow\Annotations as Flow;
+use Neos\Flow\ObjectManagement\ObjectManagerInterface;
+use Neos\Utility\PositionalArraySorter;
+
+class MaintenanceModeMiddlewareFactory
+{
+    protected ObjectManagerInterface $objectManager;
+
+    #[Flow\InjectConfiguration(path: 'allowModules')]
+    protected array $allowModuleNames;
+
+    /**
+     * @param ObjectManagerInterface $objectManager
+     */
+    public function __construct(ObjectManagerInterface $objectManager)
+    {
+        $this->objectManager = $objectManager;
+    }
+
+    public function create(): MaintenanceModeMiddleware
+    {
+        $allowModules = [];
+        $sorter = new PositionalArraySorter($this->allowModuleNames);
+        foreach ($sorter->getSortedKeys() as $moduleName) {
+            $allowModules[] = $this->objectManager->get($moduleName);
+        }
+
+        return new MaintenanceModeMiddleware(
+            $this->objectManager->get(MaintenanceModeManagerInterface::class),
+            ...$allowModules
+        );
+    }
+}
diff --git a/Classes/MaintenanceModeActiveException.php b/Classes/MaintenanceModeActiveException.php
new file mode 100644
index 0000000..48b1824
--- /dev/null
+++ b/Classes/MaintenanceModeActiveException.php
@@ -0,0 +1,10 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DigiComp\FlowMaintenanceMode;
+
+class MaintenanceModeActiveException extends Exception
+{
+    protected $statusCode = 503;
+}
diff --git a/Classes/MaintenanceModeDistributionFileManager.php b/Classes/MaintenanceModeDistributionFileManager.php
new file mode 100644
index 0000000..b38af1a
--- /dev/null
+++ b/Classes/MaintenanceModeDistributionFileManager.php
@@ -0,0 +1,16 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DigiComp\FlowMaintenanceMode;
+
+class MaintenanceModeDistributionFileManager implements MaintenanceModeManagerInterface
+{
+    public function isMaintenanceMode(): bool
+    {
+        if (\file_exists(\FLOW_PATH_ROOT . '/.maintenance')) {
+            return true;
+        }
+        return false;
+    }
+}
diff --git a/Classes/MaintenanceModeManagerInterface.php b/Classes/MaintenanceModeManagerInterface.php
new file mode 100644
index 0000000..3805675
--- /dev/null
+++ b/Classes/MaintenanceModeManagerInterface.php
@@ -0,0 +1,10 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DigiComp\FlowMaintenanceMode;
+
+interface MaintenanceModeManagerInterface
+{
+    public function isMaintenanceMode(): bool;
+}
diff --git a/Configuration/Objects.yaml b/Configuration/Objects.yaml
new file mode 100644
index 0000000..8feaa00
--- /dev/null
+++ b/Configuration/Objects.yaml
@@ -0,0 +1,11 @@
+DigiComp.FlowMaintenance:AllowByCookieModule:
+  className: DigiComp\FlowMaintenanceMode\AllowModules\ByCookieAllowModule
+  arguments:
+    1:
+      setting: DigiComp.FlowMaintenanceMode.allowCookie.name
+    2:
+      setting: DigiComp.FlowMaintenanceMode.allowCookie.value
+
+DigiComp.FlowMaintenance:MaintenanceModeMiddleware:
+  className: DigiComp\FlowMaintenanceMode\Http\MaintenanceModeMiddleware
+  factoryObjectName: DigiComp\FlowMaintenanceMode\Http\MaintenanceModeMiddlewareFactory
diff --git a/Configuration/Settings.Flow.yaml b/Configuration/Settings.Flow.yaml
new file mode 100644
index 0000000..d1fc015
--- /dev/null
+++ b/Configuration/Settings.Flow.yaml
@@ -0,0 +1,20 @@
+Neos:
+  Flow:
+    http:
+      middlewares:
+        maintenanceMode:
+          position: "after trustedProxies"
+          middleware: "DigiComp.FlowMaintenance:MaintenanceModeMiddleware"
+    error:
+      exceptionHandler:
+        renderingGroups:
+          maintenanceErrors:
+            matchingStatusCodes:
+              - 503
+            options:
+              error:
+                options:
+                  logException: false
+                  templatePathAndFilename: "resource://Neos.Flow/Private/Templates/Error/Default.html"
+                  variables:
+                    errorDescription: "The system is currently under maintenance. Try again later."
diff --git a/Configuration/Settings.Main.yaml b/Configuration/Settings.Main.yaml
new file mode 100644
index 0000000..b3b894f
--- /dev/null
+++ b/Configuration/Settings.Main.yaml
@@ -0,0 +1,8 @@
+DigiComp:
+  FlowMaintenanceMode:
+    allowCookie:
+      name: ~
+      value: ~
+    allowModules:
+      DigiComp.FlowMaintenance:AllowByCookieModule:
+        position: start
diff --git a/composer.json b/composer.json
new file mode 100644
index 0000000..4e92536
--- /dev/null
+++ b/composer.json
@@ -0,0 +1,21 @@
+{
+  "name": "digicomp/flow-maintenance-mode",
+  "description": "Maintenance mode for Flow based systems",
+  "type": "neos-package",
+  "require": {
+    "neos/flow": "^7.3",
+    "php": "^8.1"
+  },
+  "autoload": {
+    "psr-4": {
+      "DigiComp\\FlowMaintenanceMode\\": "Classes"
+    }
+  },
+  "extra": {
+    "neos": {
+      "package-key": "DigiComp.FlowMaintenanceMode"
+    },
+    "applied-flow-migrations": [
+    ]
+  }
+}